VOLTAGE TRANSFORMER

A voltage transforming apparatus includes a primary winding (3) receiving an AC voltage, a plurality of secondary windings (4a, 4b) that are different in number of turns, and a voltage conversion circuit (5) for converting an AC voltage induced in each of the plurality of secondary windings (4a, 4b). Each of the plurality of secondary windings (4a, 4b) includes a first terminal and a second terminal each having a potential that is not fixed. The first terminal and the second terminal are separately provided in each of the secondary windings (4a, 4b). The voltage transforming apparatus further includes a switching circuit (8) for selectively connecting the first terminal and the second terminal of each of the plurality of secondary windings (4a, 4b) to the voltage conversion circuit (5).